A071924 Highest m such that prime(m) divides the n-th pandigital (A050278).

749, 208, 6503705, 1831, 657, 1045880, 6503711, 239879, 375325, 7864, 45075, 7064, 2313602, 6503717, 59, 1766468, 78975, 840, 1046, 33355, 2133, 109, 107390, 56057, 6503758, 3386573, 6503759, 2044, 3386575, 158964, 2313623, 9463, 2313625, 36081

Offset: 1

Author

Lekraj Beedassy, Jun 14 2002

Keywords

• nonn
• base
• fini

Examples

			The 10th pandigital 1023457896 has prime decomposition 2^3*3^3*59*80309 and 80309 is indeed the a(10)=7864th prime, i.e., prime(7864)=80309.
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A050278.

Programs

Mathematica

PrimePi[FactorInteger[#][[-1,1]]]&/@(Select[Sort[FromDigits/@ Permutations[ Range[0,9]]],IntegerLength[#]>9&,50]) (* Harvey P. Dale, Jun 06 2018 *)

Python

from itertools import permutations, islice
from sympy import primepi, primefactors
def A071924(n): return primepi(max(primefactors(next(islice((int(e+''.join(d)) for e in '123456789' for d in permutations('0123456789'.replace(e,''),9)),n-1,None))))) # Chai Wah Wu, Dec 07 2021

Extensions

a(24)-a(33) from Donovan Johnson, Jan 25 2009

Edited by Charles R Greathouse IV, Aug 02 2010

Keyword "fini" added by Sean A. Irvine, Aug 21 2024